Electrolysis is a known method of producing hydrogen gas from water in which two electrodes are placed in water and an electrical power supply is connected to the electrodes. The positively charged electrode is called the anode and the negatively charged electrode is the called the cathode. When performing fresh water electrolysis, water decomposes into hydrogen gas and oxygen gas. Hydrogen tends to form at the cathode and oxygen tends to form at the anode.
One problem with the fresh water electrolysis is that fresh water has poor electrical conductivity, which prevents the flow of electrons from the electrical power supply, through the cathode, and to the anode. Without the flow of free electrons, the electrochemical reactions cannot occur, and water will not decompose into hydrogen and oxygen. For this reason, an electrolyte such as salt (e.g. sodium chloride) is added to the water so as to provide ions, which tends to increase the conductivity of water and improve the efficiency of electrolysis.
While salt water electrolysis is more efficient than fresh water electrolysis, salt water electrolysis is still a relatively inefficient process for producing hydrogen. As a result, salt water electrolysis represents only a small fraction of the total hydrogen production worldwide.
Increasing the efficiency of salt water electrolysis could substantially increase the amount of hydrogen produced worldwide. In particular, oceans are an abundant source of salt water and could be utilized to extract large amounts of hydrogen for use in commercial and industrial applications. However, this is not practical until salt water electrolysis becomes more efficient.
Accordingly, there is a need for new or improved apparatus and methods for producing hydrogen from salt water by electrolysis.